Navy, Japanese government practice response to an aircraft-carrier reactor leak

U.S. and Japanese technicians aboard a Japanese coast guard ship take air, water and sediment samples during a reactor-leak drill at Yokosuka Naval Base, Japan, Dec. 15, 2017. The base is home to the nuclear-powered aircraft carrier USS Ronald Reagan.

YOKOSUKA NAVAL BASE, Japan — Navy and Japanese officials have practiced the steps they’d take if a small amount of radiation were to escape from the Yokosuka-based USS Ronald Reagan aircraft carrier.

U.S. shipyard technicians teamed up with Japan’s Nuclear Regulation Authority Friday and boarded a Japan coast guard cutter to collect water, air and sediment samples from points near the Nimitz-class aircraft carrier, which recently returned to Yokosuka from its three-month fall patrol. The purpose was to practice joint radiological monitoring and data-sharing.

The hourlong drill simulated how they would respond if slightly radioactive coolant water were to leak from the carrier’s reactor. In the scenario, the Ronald Reagan’s crew responded quickly and shut a valve, halting the leak, but not before 300 liters spilled into the harbor.

“For perspective, the small amount of radioactivity that would be in this coolant water is less than the amount of radioactivity contained in two common household smoke detectors and would not adversely affect human health, marine life, or the quality of the environment,” the Navy said.

If such a leak were to happen, the Navy would notify the Japanese government and city of Yokosuka before dispatching liaisons to a nearby emergency operations center to share news about the spill to officials and the media.

The Navy would also inform Yokosuka base workers that it’s safe to continue their jobs.

Such an incident is unlikely due to the safety measures in U.S. nuclear-powered warships, said a statement from the U.S. Embassy in Tokyo. Naval reactors have four barriers working to keep radioactivity inside the ship. The reactors generally run at less than 15 percent of their rated power, and are shut down while the ship is in port.

Such safeguards have allowed the Navy to safely operate nuclear-powered warships for over 50 years while traveling over 134 million miles, the State Department said.

U.S. and Japanese technicians confer before boarding a Japanese coast guard ship to take air, water and sediment samples during a reactor-leak drill at Yokosuka Naval Base, Japan, Dec. 15, 2017. The base is home to the nuclear-powered aircraft carrier USS Ronald Reagan.LEON COOK/STARS AND STRIPES